Waterjetting 17e - Liposuction and other medical uses

One of the advantages of using high-pressure waterjet streams as a cutting or cleaning tool is that, unlike more mechanical devices, there is much less need to apply additional force through the tool in order for it to work. This was one of the considerable advantages that waterjetting had when it was first introduced, and married with robotic arms in cutting different materials. Early robots had little arm strength – it was a major constraint in the design of new equipment since we had to recognize that, for example, in order for the arm to keep its precision and accuracy we could apply no more than ten or twenty pounds of thrust through the nozzle. This limit was overcome when the power was applied from a jet at 50,000 psi pressure, over a very small nozzle diameter and meant that the combination of robot controlled manipulators and jet nozzles could cut complex shapes in materials ranging from shoe leather through carpet, through automobile and aircraft components.

That advantage remains as tool size is shrinking and waterjets are gaining an increasing role in the medical part of the waterjet market. I had mentioned, in previous posts, how waterjet systems are increasing being used to debride wounds, remove cancers and help expose blood vessels in liver surgery. But with the small sizes of nozzles that are now available, it is also possible for jets to be transmitted through the small tools used in laparoscopic (keyhole) surgery. As a result surgeries can be smaller in scale, less traumatic to the patient and faster to heal because of the smaller footprint of the surgery. In liver surgery, as an example, the increasing use of waterjets in resection has reduced the amount of transfusion liquid required by more than 75%.

Tool sizes have continued to shrink, and thus it is now possible to use the jets in surgeries beyond those that we originally envisioned. For example there have been a number of studies over the years on the use of waterjets to cut bone. One of the problems in hip, knee and other joint replacement surgeries is that the faces of the cuts need to be quite precisely aligned in order for the prosthesis to fit into place. With surgeons using a common saw to cut through the bone, the cut can deviate from that clean alignment. Further the saw can generate heat that can damage the bone and tissue along the cut line. High pressure jets both cool and help align the cut to minimize misalignment of the cut line.

Other tissues are more easily cut, and waterjets are being used more extensively in tumor removal and in cutting the ligaments that hold organs, such as the gall bladder or prostate in place, making endoscopic surgeries easier.

Other body tissue can also be removed. As I have updated the range of applications for waterjets in the medical field over the years it is only now that I am finding references to the use of waterjets in liposuction. Waterjet Assisted Liposuction (WAL) has been described as:

Using a fan-shaped laminar jet, the body-jet® simultaneously irrigates and aspirates fatty tissue. The gentle separation of fat cells from connective tissue minimizes trauma to the patient. At the same time, significantly less infiltration fluid is needed with the WAL procedure as compared to traditional methods, helping to reduce exposure to tumescent fluid, minimize swelling, allow real-time precise contouring, and dramatically shorten procedure times.

Other sites provide similar comments:

Body-Jet Water Liposuction relies on the power of highly concentrated water to gently dislodge and remove fat cells from the body. Using water-jet technology, fat is removed from the body with significantly less force than older liposuction techniques. The power of the water-jet detaches fat cells from their surrounding tissues, allowing the suction cannula to move freely. This limits the possibility of trauma to surrounding tissues, including skin, muscles, nerves, blood vessels, and septal attachments. . . . . . Because the process is so gentle, Body-Jet Water Liposuction is typically performed as an out-patient procedure under local anesthesia. On average, the entire procedure takes between 30 to 45 minutes for each part of the body that is treated. The majority of body-jet water liposuction patients find that they can return to their regular activities immediately following the procedure. In fact, Body-Jet Water Liposuction has been called “lunch break lipo” because most patients are able to have the procedure performed and immediately resume regular activities.

There is a video about the procedure here .

As I mentioned earlier in regard to back surgery the small amount of damage outside of the region where the jet is cutting means that many of these procedures can be carried out as outpatient surgery with the patient being able to leave without hospitalization. Further because the jet works by discriminately removing the desired tissue without damage to surrounding hard tissue, and it can reach “around corners” to flush out cavities it has been reported, for back surgeries:

In treating spines, where the disc is removed before carrying out spinal fusion the waterjet was able to get out some 96% more of the soft tissue that was achieved by conventional means.

More refined applications, such as in breaking up blood clots in thrombectomy have also now been developed, The technique appears to be more widely tested in Europe than in the United States at the moment. It has been approved for use in the United States.

Each year in the U.S., approximately 600,000 patients are diagnosed with deep vein thrombosis. Complications range from severe pain and limitation of mobility, to limb loss and even death. Moreover, 200,000 people die from pulmonary embolism (PE) each year, which occurs when venous thrombus migrates to the lungs and blocks blood flow. . . . . . The FDA's clearance of AngioJet thrombectomy . . . . . gives doctors a powerful tool to restore flow to blocked veins. Patients may benefit from faster resolution of leg pain and reduced risk of complications.

There are, in short, increasing applications for high-pressure waterjets in the medical field, and the advantages which the tool brings to cutting in more mundane applications seem also to carry over into surgical applications. It has only, however, been after smaller and more precise tools have been developed that this set of applications has evolved, and it will be interesting to see how much longer the list grows in the years to come.

Tech Talk - Coal begins to fight back

As the President moves further into his second term, he appears to be growing more willing to tackle the concerns that his supporters have over projected Climate Change over the next century. Given the makeup of the Congress it is likely that this will be through additional regulation and Executive orders. There have been a number of reports that have documented the projected costs of climate change. Some of these have been relatively modest in statement. The Copenhagen Consensus Center, for example, noted:

Climate change is real and man-made. It will come as a big surprise that climate change from 1900 to 2025 has mostly been a net benefit, rising to increase welfare about 1.5% of GDP per year. Why? Because global warming has mixed effects and for moderate warming, the benefits prevail. The increased level of CO₂ has boosted agriculture because it works as a fertilizer and makes up the biggest positive impact at 0.8% of GDP. Likewise, moderate warming avoids more cold deaths than it incurs extra heat deaths. It also reduces the demand for heating more than increases the costs of cooling, totaling about 0.4%. On the other hand, warming increases water stress at about 0.2% and negatively impact ecosystems like wetlands at about 0.1%. Storm impacts are very small, as the total storm damages (including naturally caused storms) are about 0.2%.

As temperatures rise, the costs will rise and the benefits decline, leading to a dramatic reduction in net benefits. After year 2070, global warming will become a net cost to the world, justifying cost-effective climate action.

This, of course,led The Guardian to stress the post-2070 part of the comment. On the other hand there are the projections of the latest IPCC report (available here) that suggest that costs are already present in the global economy and that they see impacts ranging from a possible fall of 2% in global economic growth, as well as impacts on health and agriculture.

The projections, of which there are many, have focused on the need to cut greenhouse gas emissions and have moved governments around the world to take steps to reduce gas emissions, without a lot of comment from the industries most effected by the proposed regulatory changes. It appears that this relatively low key approach is going to change as a new report prepared for the American Coalition for Clean Coal Electricity (ACCCE) provides some strong factual discussion points that argue rather for the benefits of carbon use, and contrast these with the costs.

It has become politically popular in recent years to increasingly demonize the fossil fuel industries, and particularly the coal industry. And I have suggested, in the past, that this was an over-reaction. However it is of value to rational discussion of the issue to recognize the points that Management Information Services have put forward in this report.

Much is made of the increased fuel use that continues to power the Industrial Revolution as it continues to spread into under-developed countries and brings their standards of living up to those enjoyed by many in North America, Europe and the more well developed countries. The transition to the better standards of life is considered to need an energy consumption, per capita, of 4,000 kWh per year.

Figure 1. The UN Human Development Index and per Capita Electricity Use (America's Power )

When one considers the relative benefits of the use of power it sometimes help to recognize the mind-set of those making the comparison. The view of someone just gaining access to electric power, and who built a windmill to provide that power, reflects a greater recognition of the benefits of electricity than sometimes seems to be currently politically correct.

The benefits brought by the available power that is now in individual hands as a result of the Industrial Revolution are manifest in virtually every aspect of our daily lives. To maintain and spread that wealth of benefits through the expanded use of electricity to an increasing global user market the IEA projects that there will be an increase in virtually all power sources for electricity over the next twenty-five years.

Figure 2. Projected Electric Power Generation by Energy Source (America's Power )

However one of the impacts of increasing regulation, and the drive to switch to alternate, renewable power sources in Europe has already been an increase in the cost of that power. This is already leading the European Union to review their policies since increasing power costs lower the competitive position of European industries relative to those of countries (such as the USA) with lower power costs.

Within the United States the report concludes that there is a negative correlation between electricity prices and the economy with a suggestion that a 10% increase in electricity prices will cause a 1 % drop in GSP. (This is an awkward argument to make given that the economies of places such as Massachusetts are significantly better with an energy cost of over $0.14/kWh that those of West Virginia where the cost is about $0.08 per kWh – though the argument is about relative change).

But the increases in power costs do not just impact the competitive advantage of industry. As prices rise, so the poorer segment of the community find it harder to meet all their living needs. There is a graph that shows their choices:

Source: National Energy Assistance Directors’ Association. Figure 3. Potential Health Impacts of Increased Energy Costs on Low Income Persons (America's Power )

It is the broad use of coal that keeps the prices of power in many countries low, and the ability of many to utilize a domestic resource allows developing countries the opportunity to climb the ladder faster than the rates that they would be able to achieve without this resource. It should be remembered that over the course of the changes brought by industrialization since 1750 (as the report notes):

From 1750 to 2009, global life expectancy more than doubled, from 26 years to 69 years; global population increased 8-fold, from 760 million to 6.8 billion; and incomes increased 11-fold, from $640 to $7,300. . . . . . . in the U.S. from 1900 to 2009 population quadrupled, U.S. life expectancy increased from 47 years to 78 years, and incomes (denoted “affluence”) grew 7.5-fold while carbon dioxide emissions increased 8.5-fold.

The reality of the next decades is that coal and the other fossil fuels will, over the next twenty-five years, remain the basis for electricity generation for a significant portion of the global economy. This is likely to be particularly true for those nations that will grow the most in population and GDP over that interval.

By discounting the benefits that these improvements in life will bring to those countries, and focusing more on the hypothetical costs of anticipated problems the Administration has made a case for changing the energy mix. It is interesting to see that the industry that it likely to be most changed by their policies is now beginning to publically and with facts, shown willing to rebut some of those arguments.

Waterjetting Technology 17d - Some medical applications - don't blink!

Our discussion on the ability of high-pressure waterjets to remove some materials without damaging others has, as I noted in the last post, found some applications in the medical field. The example that I provided in that post dealt with the use of waterjets to dislodge material in the cleaning of wounds, or to carefully excise thin layers of burnt flesh without doing damage to the underlying tissue. I also pointed to the ability of a waterjet to remove weaker diseased tissue, such as brain and skin tumors, without damaging the surrounding tissue, which is healthy and thus able to resist the pressure of the cleansing waterjet.

There are a number of other applications in the medical field which have developed from these advantages. The first is in surgery on the liver and kidneys in particular. In these organs there are generally a large number of blood vessels that carry blood through the organ so that the blood can be cleaned of impurities. The difficulty that this creates usually occurs in cases where the organ becomes diseased. Medical treatment recommends that the diseased volume of the organ be removed, and the historic method for doing this has been to take a scalpel and carefully cut around the diseased region, so that it can be lifted out. This is often referred to as liver resection.

The problem that this creates is that, in the process of cutting out the diseased part of the organ, the surgeon must also cut through the blood vessels in that part of the organ. Because they are buried in the organ, it is not clear where these vessels are, and they are conventionally difficult to isolate. Early work in finding an answer was carried out in Japan.

However blood vessels are relatively tough (and when full of blood require pressures of around 2,000 psi or more to penetrate) whereas the surrounding tissue is much softer. As a result – using the same conceptual approach that I described last time for the removal of skin cancer, a surgeon can remove the tissue from around the blood vessels and along the projected line of dissection, without cutting through the vessels. Tests during brain operations have shown that as long as the pressure is kept below 300 psi there is no damage to any of the vessels in the brain, and similar conclusions are likely to hold for other organs in the body. The jet was, however able to remove diseased tissue, while leaving healthy tissue.(In these surgeries the jet is on the order of 100 microns in diameter, and as a result uses very little water during the operation.)

Figure 1. Japanese surgical removal of liver tissue around blood vessels of the liver, exposing them so that they can be tied off, before being cut, thereby significantly reducing blood loss.

Clinical trials rapidly spread around the world, Papachristou had published on the technique in 1982 when, after 75 trials with dogs it was tried in four male human patients. At the time it was noted that there was significant reduction in blood loss. This is fairly critical in older patients (who are more likely to need these operations) since large losses of blood can induce shock, and can be fatal. Blood loss is the most common complication of the surgery and consequent cause of death (which now runs around 5%, but was higher prior to waterjet introduction).

It also impacts long-term survival and post-operative complications. (Historically the problem was addressed using what is known as the Pringle manoeuvre in which all the blood flow to the liver is halted by clamping for the period of the operation. However this can only be applied for limited amounts of time and is of limited effectiveness.) Using a waterjet approach has the advantage, over ultrasonic and cavitating techniques, that the path cut through the liver is narrower and the vessels are more clearly delineated. At the same time, as figure 1 shows, the sides of the cut are relatively clean and well defined. The jet is able to handle the tougher tissue in a cirrhotic liver either through a longer residence time, or by raising the pressure of the jet by about 150 psi.

The very narrow cut achieved by the waterjet has another useful feature in that the jet will, in fibrous tissue, push apart the fibers rather than fusing them, as would be the case with laser cutting. This has advantage in eye surgery where any such fuse points can cause scarring that interferes with future vision, while the separation of the tissues with the jet does not carry that problem.

Figure 2. Precision cutting across the face of the eye at a jet pressure of 20,000 psi and with a jet diameter of 10 to 100 micron.

The technique was first announced in 1994 and animal tests had been successfully completed by 2001. Because the jet cuts so fast (less than a second per cut) there is no tissue loss. (The operation uses a device that fits to the eye to hold the lens in the right position to make the cut).

The technique has not, however, been that successful in the field as has another application, that of removing herniated disks in the spine. The technique uses a procedure known as Hydrocision. It is interesting to read a quote from an article last November on the technique:

"It's basically a high-velocity water jet eroding system," Kevin Staid said about the medical device that his North Billerica, Mass.-based company makes. "And this is our first entry into the area."

With HydroCision, a jet of saline solution comes out of a nozzle that is 0.005 inches in diameter -- "slightly larger than a hair" -- and can cut away protruding disc tissue that can cause the back and leg pain without an actual blade.

"Just the energy of the jet would be doing the cutting," said Staid, an engineer. "In our case, the water is going about 600 miles an hour and has the ability to cut quite effectively."

The advantages of the 20-minute outpatient procedure are: No hospitalization, quicker recovery times, less pain, no surgical trauma to the back muscles and no general anesthesia.

"There is no muscle damage, no bone removal, no nerve root manipulation ... and the size of the wound is approximately 4 mm," Kowalkowski said.

The use of the tool is sufficiently popular that in 2009 the company (Hydrocision) announced that the tool had been used in more than 40,000 procedures.

I’ll give other medical examples in the next post.

Tech Talk - Production, Profit and Projection

As we move steadily through the first month of this new year, US production of crude has continued to increase, with the EIA now showing levels of around 8.2 mbd production.

Figure 1. US Domestic Crude production through the end of 2013 (EIA TWIP)

Finished gasoline production has been floating around a level of 9.2 mbd.

Figure 2. U.S. Finished gasoline production at the end of 2013. (EIA TWIP)

At the same time ethanol production continues at around 0.9 mbd.

Figure 3. U.S. Ethanol production at the end of 2013 (EIA TWIP)

US gasoline demand, on the other hand, has fallen below 9 mbd, in the normal seasonal decline during the winter months.

Figure 4. US gasoline demand at the end of 2013. (EIA TWIP)

In the latest Director’s Cut of the news from the North Dakota Department of Mineral Resources the state reports that production averaged 973 kbd in November, up from 945 kbd in October). The rig count is running around 190 rigs (below the all time high of 218 – roughly 18-months ago) and the agency notes that companies are moving toward a higher density for horizontal wells as a means of enhancing oil recovery. They estimate that at the current rig count there will be enough work under this program to sustain the industry for more than 20-years. However production will decline as the richer spots are drained, and in the most favorable scenario production will rise for another 2 to 3 years before stabilizing and then declining. At present the rate of growth in production is in the range of 300 kbd per year.

Figure 5. North Dakota Oil Production – historical and projected (ND Dept of Mineral Resources )

This is roughly similar to the growth in production from the Eagle Ford Shale in Texas over the past year.

Figure 6. Changes in production from the Eagle Ford Shale in Texas (Texas Railroad Commission )

Growth in production from the deep waters of the Gulf are likely to be closer to 50 kbd. Even combined, and recognizing that there may be some additional production from developing shale prospects, it is difficult, as the above three regions hit production peaks in the near future, to anticipate that US production will increase by the 2 mbd that is projected by some forecasts.

Some of this doubt comes from North Dakota agency itself, which has some concerns over the continued ability of the industry to attract drilling capital, as well as the impact of additional regulations. This limit of available funds is something that Gail Tverberg has pointed out in a recent post. Shell is only one of the major companies recognizing that the increasing costs of development in more difficult parts of the world are not being offset by compensating increases in production, price and profit. As operations around the world continue to attest, (offshore Brazil being but one example) just because the money is invested does not mean that production will of a certainty arrive on the original date forecast, nor will it be at the original price estimated. In the case of Brazil, while new fields show the promise for the future with a steady increase in the reserves that the country projects, this has yet to be reflected in increased production.

Figure 7. Growth in projected reserves offshore Brazil over the past 30 years (Offshore )

The problems of development are being blamed on a lack of available drilling rigs as well as budget constraints. This may be a considerably simplified version of the realities which are likely to continue to see delays in production against target figures into the medium term future. This is unfortunate since there remain few places where global production can be expected to increase in the near future.

In the latest Monthly Oil Market Report (MOMR) OPEC notes that non-OPEC supply growth is anticipated to be 1.2 mbd this year, with the bulk of that growth coming from the United States, Canada, Brazil and the two Sudans. Oil production from the Canadian oil sands is anticipated to reach 3 mbd by 2015 on its way to a total production estimate of around 6 mbd by 2035, at an approximate growth rate of 100 kbd per year.

Figure 8. Anticipated growth in Canadian oil production (NEB )

Perhaps more than most the Canadian growth is likely to follow the projected path, although there, as in other parts of the world, the need to ensure future capital for the increasingly expensive operations, and the provision of sufficient infrastructure to handle the increased production are matters that will continue to provide caveats to the overall levels achieved.

And as regards the increase in production from Sudan and South Sudan, certainly the conditions in South Sudan are not encouraging to hopes for increased production at any time in the near future. Fighting in the regional capital of Malakal shows the increasingly tribal nature of the conflict and this may well indicate that fighting will not easily be stopped and order (let alone oil flow) restored. This is of concern to China, which imported some 14 million barrels of oil from the region in 2013 but is now faced with the problems of sustained investment in the face of lost production and facilities after seeing a similar collapse in production from Libya. And while these problems are considered relatively small at the moment, at this time when global production and supply are relatively closely tied, the continuation of problems will mean the China must look elsewhere for that production, with consequent impacts on overall prices.

The problem, as the very short list from OPEC illustrates, is that there are not that many places around the world where increased production is likely and where China can invest to achieve the levels that it anticipates that it will need as demand continues to grow. And as the market becomes more competitive, so prices are unlikely to decline much (apart from regional short term issues such as the recent desire in the US to produce more diesel from refineries). Yet while this will give some reassurance to those seeking to invest capital in the industry it comes at a time where there remain concerns over regulation in some countries, and conflicts in others both of which cause investors to hesitate in their commitment. The problem is that there aren’t that many alternative strategies that hold much hope for working.

Waterjetting 17c - Discriminate cutting of tissue

In the last two posts I have noted that, by tailoring the pressure at which a waterjet is aimed at a surface, it is possible to discretely remove different layers that cover that surface, while leaving the underlying layers undamaged. The examples extend from removing individual layers of paint to the rubber left on a runway after planes have landed. But this idea also works in the removal of damaged concrete from bridge decks and garage floors. Here it is the ability of the jet to grow the longer cracks in the damaged concrete that makes it able to discriminate between the good and bad parts of the deck.

The idea can be extended into other areas that are not quite as obvious. And it began with a conversation with my dermatologist – Dr. Van Stoecker. We were discussing the change in state of different tumors when I brought up the discriminatory ability of waterjets. And so I went home and tried a simple experiment. I took an apple and bruised it – and left it for a couple of days. (The pictures come from a repeat of the experiment that I carried out today).

Figure 1. Bruised apple, showing the darkened damaged flesh under the skin

Then I removed the skin over the bruise and using a water pick washed away the soft damaged tissue, while leaving the healthy tissue undamaged, since the jet did not have enough power to remove it.

Figure 2. Showing the peeled region around the damaged part of the apple, and the old model WaterPik used for the demonstration.

The process was a little slow, and since the tip was hand-held and not rotating (the better way to ensure total areal coverage) took longer than it would with a spinning jet.

Figure 3. Partially cleaned apple.

The pulsating jet is manually oscillated over the apple surface, and cuts down through the softer flesh, but is not powerful enough to remove the healthy apple tissue beneath it.

Figure 4. The apple after the damaged flesh had been removed. Because of the simple manual manipulation the cleaning of the final surface was not quite as thorough as is achieved with a spinning head. The procedure takes varying amonts of time depending on the pulsation setting and the type of apple being used – this was a Granny Smith.

A water pick operates at a relatively low pressure, but the demonstration was sufficient that Dr Stoecker obtained an excised human skin tumor and we carefully cleaned the tumor surface, aspirating the spent water and debris using a small version of the vacuum system that we used to collect radioactive waste from underground storage tanks. When the tissue was then sent away for analysis it turned out that the water had effectively removed all the diseased tissue – which is softer – while leaving the healthy tissue in place.

Testing progressed through testing on dogs, and the concept was ultimately patented and was licensed.

One of the advantages of the tool, and the approach is that the jet will penetrate and remove the small tendrils of cancer that can spread out from the main tumor since the jet will follow these paths and remove the soft tissue content, while leaving the stronger healthy flesh. This has the benefit of reducing the scarring of the flesh in the vicinity of the tumor, and thus the amount of subsequent cosmetic treatment.

The argument for reduced excision of healthy tissue is equally or perhaps of more concern where the tumor lies in the brain, and colleagues in Germany have carried out operations on individuals to evaluate how effective waterjet removal (hydro-surgery) (Waterjet dissection of the brain: experimental and first clinical results. Technical note. Piek J, Wille C, Warzok R, Gaab MR.) No complications were found with the first nine patients who received this treatment.

The use of pulsating jets, of the WaterPick variety and at higher pressures has found increasing use for other purposes. Before the recent popularity of chemical washes it was, for example, shown that the use of a pulsating jet to flush wounds helped both remove any foreign matter still in the wound (particularly with “gravel rash” type injuries) and to lower the bacterial count.

Figure 5. Change in relative bacterial counts after conventional and pressure washed wound treatment (From PTJournal)

For this to be effective jet pressures had to be higher than 25 psi. Specialized equipment has now been developed for these uses, which have been shown to provide the benefits of: - shortening of the wound healing process, - reduction of the scar tissue, - low stress effects for the patients because the treatment is relatively painless.

Two different tools, the Debritom and the Versajet have been marketed for use in cleaning skin injuries (and while photos exist – for example here, I will recognize that some readers may be sensitive and will forego showing them.

The Versajet is a slightly different concept in which a very small high-pressured jet cuts across the face of the instrument and back into a collection chamber, so that it can peel off thin layers of necrotic and other undesired tissue and clean up wounds, particularly with burn injuries, more positively. The vacuum created by the jet passage into the chamber helps collect the debris.

Figure 6. Schematic showing the operation of the Versajet system.(Smith and Nephew )

Precision cutting and discriminatory cutting of flesh and other parts of the body have grown in application as the ability to manufacture smaller and more precise component,s that can operate at higher pressure, have been developed.

I will conclude this short section on some of these developments in the next post.

Tech Talk - Coal mining continues to produce

Sadly I was away from home last week to attend a family funeral in Northumberland where, for the past nine generations including mine, our family have been miners. The funeral was for my father’s sister, Linda, who had documented early life in the mining village of Ashington in her books “A Tune for Bears to Dance To,” and “The Pit Village and the Store.” The latter was made into a docu-drama for British Channel Four television. The hotel at which we stayed was next to the Woodhorn Mining Museum which has been built around the colliery offices from the old mine. The rest of the property has been turned into a nature park – with a little twist.

Figure 1. Part of the old mine site, now the Queen Elizabeth II Country Park, with a 40 acre lake. Note the wind turbines in the background – all but one of the 14 were turning during my stay. (Hotel on the right)

The site is also now home to considerable bird life – including over three dozen swans that I counted as I meandered around the lake.

Figure 2. Some of the birds on the lake at Woodhorn

Much of this part of Northumberland has changed considerably since the time – over 50 years ago – that I was an Indentured Apprentice in the National Coal Board working at Seghill Colliery, though on day release once a week to Ashington Technical College. One of the greater changes is illustrated in the background to a painting of my father that my aunt painted.

Figure 3. My Dad as Undermanager at Ashington (note the yard stick, the safety lamp is hidden by the coat). (Linda McCullough-Thew)

The large mounds are the pit heaps which were scattered all around the road as the bus carried me from Newcastle to the pit. They are all gone now, and the land is restored and, as the pictures above testify, now visually contaminated by the latest form of energy generation, though that doesn’t seem to worry the red squirrels and the geese.

Figure 4. Pit heap dominating the miners houses (Sunderland Public Library)

I thought of that as the recent reports on the devastation that mining creates are once again headlining the problems as new and enlarged lignite mines are developing in Europe. The transition to mining lignite, which contains considerable quantities of water and is a geological precursor to the black bituminous and anthracite coals that are preferred, is coming because it is considerably cheaper than alternate sources and nations have it at hand, instead of having to spend currency on importing alternate and increasingly expensive fuels from elsewhere. The reason that lignite is attractive is that the black coal seams that used to be mined in much of Europe have been mined out at currently economic depths, and lignite – even though less energy intense – has become an economically viable alternative.

To mine the surface deposits Europeans rely on the Bucketwheel Excavator (video here) with one machine replacing 40,000 men with picks and shovels (the way I was initially taught to mine). The overlying rock and soil (overburden) is first removed and stored, and then, once the coal has been removed, the land is restored with very stringent requirements for the condition of that restoration, so that in many cases the stone walls around the fields are replaced and the appearance of the land is similar to what was there before.

At present surface mining is becoming the dominant method for coal production. The thick seams in Wyoming and Montana have huge reserves, and the coal is very simple to mine and remove. Once mined it is trucked away from the machines and loaded into rail cars which then carry the coal around the nation. Because this coal has a low sulfur content it has proved competitive even against the more local coals of the East, which must often now be expensively mined from the underground. As the Wall Street Journal recently noted two counties in Wyoming now account for 40% of the US coal mined, while underground mines are closing in Appalachia.

After seeing a drop in coal production of around 9% as coal fired power plants were replaced by natural gas in the 2011 to 2013 time frame, the EIA is now projecting that US coal demand will increase by 3.6% this year, as natural gas prices rise. This will be followed by a 2.5% decline in 2015 as the new EPA regulations bite harder in driving the closure/transition of power plants. However US natural gas prices continue to be much lower than those in most of the rest of the world, and thus, as the WSJ notes , overall coal production in the USA is likely to stabilize around current levels for the next three decades, while domestic demand reduction is offset by increasing demands for coal from other countries which will continue to find it a cheaper alternative.

Much of the alternative replacement fuels for coal (and in some cases nuclear) are presumed to be from the increased levels of shale gas that are being produced in the United States, and which are projected to become domestic sources of fuel in many other countries around the world , including Europe. However while the plans and actions to close coal fired power plants proceed apace the rate and scale at which alternate sources of energy, particularly European shale gas, will appear are much less certain.

And in the interim, as coal mines have found better ways of processing the coal to meet power station demands, the potential for growth still exists, as the recent example in the Illinois Basin shows, where Sunrise Coal are planning to open a new underground mine in Vermillion IL this year, producing around 3 million tons of coal a year. The mine will use room and pillar mining to ensure that there is no surface ground subsidence, which can be a problem in the Illinois Basin.

And those who anticipate that China and India will reduce coal demand in order to overcome the problems that they have with air pollution, should remember that air pollution in the UK was at least as bad in the early 1060’s but by changing the way in which coal was burned the air was cleaned, and Britain continues to rely on coal for a significant portion of its electrical power.

Waterjetting 17b - Removing layers

In the last post I discussed the ability of high pressure water to penetrate through the rubber layers that coat a runway, after planes land, and then remove it, without damaging the underlying concrete.

This ability of waterjets to be able to remove individual layers of a coating, without damaging the layers beneath (the substrate) is one that has found a number of different applications within the cleaning industry. One of the more obvious is the ability to remove the paint layer from underlying surfaces, without damaging the material which the paint covers. In fact, if the treatment is careful enough we have, in some cases, been able to remove individual layers of paint while leaving the less weakened underlying paint primer in place. And to demonstrate a point we showed that it was possible to remove (as desired) the top paint coat, the primer coating and then if there is metal corrosion also to remove the top layer of metal from a surface. It just depends on what is desired and “how clean is clean.”

One significant difference between cleaning and paint removal relative to cutting is that the thickness of the target material to be penetrated is generally much less than that found in other applications. Given that there is also a concern with contamination of large volumes of water, that must be collected and disposed of, the use of higher-pressured systems has a number of advantages.

One significant one is that, with the use of very small nozzles the distance over which the jet has power becomes significantly less (consider that the effective range is likely to be less than 150 jet diameters and that orifices on the order of 0.005 inch in diameter are used) and this minimizes the amount of possible damage that the jets might cause through over-cutting if there is an unanticipated weakness in the substrate material. With small ultra-high pressure jets cutting through the small depth of the desired material at a faster rate, the optimal cutting traverse speed for the nozzle over the surface increases. This in turn means that there is often a considerable advantage to mounting the nozzle array on a bar that is then spun at high speed giving a greater areal coverage and also allowing the assembly to be contained within a vessel that can be attached to a vacuum system that extracts both the water and the debris.

Figure 1. Simplified illustration of the combination of a spinning waterjet system with vacuum extraction to leave a cleaned and relative dry surface after passage.

The marriage of high-pressure water systems with vacuum extraction of the water and debris is one of the changes that are now happening in the industry, but which are, as yet, only in their infancy relative to the potential that with be developed as their use becomes increasingly commercialized. The largest market at the moment is in hydro-excavation, where relatively low jet pressures (2,000 psi) are used to disaggregate soil. Note that while this video gives you some idea of the concept it is using way too much water and if the head and suction pipe are better integrated much more impressive volume removal rates with much lower water usage rates can be achieved. (And as a minor quibble vacuum systems work best with water targets where the head is no more than about quarter of an inch from the top of the water surface.)

The technology is being advanced as more self-rotating heads are integrated into the system, since these give a much faster coverage of the ground without the need for bulky drive unit down at the operating end of the system. One of the advantages of the system is that the water can be set at a pressure that will not damage underground cables, sewer pipes or other passageways that run through the soil, and which would otherwise be vulnerable to the blade of a conventional mechanical excavator.

But the potential for this combination goes much further than these early tools. On a larger scale they can be integrated into the systems that are now used to remove fouling and residual paint from ships hulls but the use of higher pressures also increases the range of materials that can be removed.

For example in hydro-demolition one can set the operating pressure of the system so that, at a pressure of around 11,000 psi the waterjets will remove the damaged material from a garage floor or bridge deck, but where the jet does not have enough pressure to cut into the healthy concrete in the main body of the slab. However, even with vacuum material removal, there are two initial disadvantages to this system. The first of these is because of the large volume of water that must be removed as the jets cut over the surface, the second comes with the range of the larger jets at these lower pressures which mean that, should the damage extend beyond the depth anticipated, the jets can cut down through the concrete slab and remove much more material than desired or budgeted for.

Raising the jet pressure, while removing the discriminatory nature of the jet cutting to some extent does overcome the two disadvantages in that the material is removed with much less water, and at a faster rate. Also, as mentioned above, the smaller jet size means that the range of the jet can be carefully controlled , so that if the specification is that concrete only be removed to half-an-inch below the rebar, for example, then the jets can be controlled to achieve this depth of removal on a consistent basis.

With those thoughts in mind we will continue to progress down this thread in the next post in this series.

Tech Talk - Predictions

From time to time I have written about the dubious assumptions that lie behind some of the predictions made by Energy Agencies and some of the larger oil producing companies as they predict the energy supplies and demands of the next few years.

It is relatively simple to make those criticisms given that one has only to compare ongoing reality with the assumptions to be able to judge that the future is unlikely to be as rosy as any of these folk imagine.

However there is this strong tradition of making the odd prediction at the start of the New Year. Yet having just spent about 2 hours digging snow out of my drive (an hour and a half for the first session which moved most of the snow and then thirty minutes to remove all the snow shifted back into the drive when the snowplow came by clearing the center of the road) my creative buds are a little slow this evening, but I would suspect that it is not hard to make one or two suggestions, and then go back and so how they panned out.

Last year I was quite pessimistic about the future, given the pull back in Arctic drilling following the grounding of the Shell drillship and had some question on the stability of the domestic production levels. Well a year later the situation in the Arctic has perhaps grown a little less encouraging for those who would anticipate early development of those resources, but on the other hand domestic production has continued to increase.

For next year I suspect that the situation with China, in terms of its attitude to acquiring sufficient energy reserves, will not improve. There are already suggestions that China will adjust its position in regard to the importation of Iranian oil and may increase purchases, despite the ongoing sanctions. Similarly it is refusing to recognize arbitration in its dispute over ownership of the China Seas (East and South). To keep the projection vague (and thus less likely to be too far off) I would expect that this will get worse over the next year, and the steps China is willing to take to ensure future energy supplies will become more obvious.

In this regard I suspect China will continue to beat out India in the pursuit of available resources around the world, though the consequences for this in India won’t likely become evident for a couple of years yet.

There will likely continue to be enough available crude to meet demand through next year (depending on how the various conflicts in the different countries of the Middle East develop) but it may be the last year in which this holds true. With the Kingdom of Saudi Arabia determined to hold production at a maximum of around 10 mbd, with Iraq increasingly troubled by growing sectarian violence and with other regional countries similarly destabilizing there are only a few places where increased production can be brought on line to meet demand – and that problem may become evident in 2015.

So having made a couple of relatively obvious suggestions let’s see how 2014 turns out for us all – though I hope it brings you Prosperity and Success!

Waterjetting 17a - Runways and discriminatory cleaning

Welcome back as we begin a New Year, and I hope that it brings Prosperity and Happiness to you and yours and that it brings much success.

Somewhere within the celebrations of the last couple of weeks water has played a considerable role, probably largest in the many different ways in which it was used to clean items –either before or after use. Water, often with a bit of soap, has been one of the earliest cleansers helping to loosen and dislodge dirt as the flow passes over the surface. There have been studies in the past which suggest that there is little advantage to the use of antibacterial soaps over less expensive conventional soap. Although the initial study was in 2005 it has only been within the last week that the FDA has told manufacturers of antibacterial soaps and washes that they have to demonstrate that they are both safe and effective. They note:

In fact, there currently is no evidence that over-the-counter (OTC) antibacterial soap products are any more effective at preventing illness than washing with plain soap and water, says Colleen Rogers, Ph.D., a lead microbiologist at FDA. Moreover, antibacterial soap products contain chemical ingredients, such as triclosan and triclocarban, which may carry unnecessary risks given that their benefits are unproven.

"New data suggest that the risks associated with long-term, daily use of antibacterial soaps may outweigh the benefits," Rogers says. There are indications that certain ingredients in these soaps may contribute to bacterial resistance to antibiotics, and may have unanticipated hormonal effects that are of concern to FDA.

In light of these data, the agency issued a proposed rule on Dec. 16, 2013 that would require manufacturers to provide more substantial data to demonstrate the safety and effectiveness of antibacterial soaps. The proposed rule covers only those consumer antibacterial soaps and body washes that are used with water. It does not apply to hand sanitizers, hand wipes or antibacterial soaps that are used in health care settings such as hospitals.

The debate over the use of chemicals with water, rather than just relying on the mechanical force of the water to dislodge dirt (used generically to include bacteria and other undesired coatings) or the combination of water with a mechanical action (using a brush or rubbing hands together) has been evaluated in many circumstances, with different results. One path will form the thread for the next few posts, and it will take us to a perhaps unexpected product line. Given that this is the season when a lot of us travel, let's begin at an airport.

Figure 1. Plane landing at airport – note the puff of smoke from the tires (Seattle Times)

When a plane first makes contact with the end of a runway, as it comes in to land, the wheels are not rotating very fast on contact, and so there is a small smear of rubber left on the end of the runway as the tires are dragged up to the right speed by the movement of the aircraft over the tarmac. (A plane can lose a pound of rubber per tire on landing).

Over a period of time this thin layer of rubber starts to build up over the surface, covering and smoothing the rough asperities that allow subsequent tire impacts to grip the runway, and making the surface slick and less tractive as a way of slowing the aircraft. As a result planes can start to hydroplane in rainy conditions and several major accidents have been blamed on this layer being allowed to grow too thick and become a dangerous surface.

For many years the practice was therefore to bring out different chemical trucks to spray the surface and a recent operation in Port-au-Prince describes the operation.

The chemicals that the team used were environmentally safe and effective in cleaning rubber deposits from the surface. The chemicals were sprayed onto the airfield and then scrubbed, brushed and worked into the rubber deposits for approximately four hours. The chemicals loosened the sticky rubber buildup into a soft gel that was then removed from the runway with a brush and water onto the shoulders of the runway. . . . . .

The AOS Research Group has developed a C-130 deployable chemical rubber removal system that is light, compact and requires no in-theater support other than fuel and water. AFCESA provided $125,000 in Research and Development funds to evaluate the rubber removal system in actual expeditionary environment. Four team members (Figure 2) traveled to Haiti and used the rubber removal technology to remove rubber build-up from the runway. In three days (approximately three eight hour shifts) they cleared 125,000 square feet on the west end of the runway and 75,000 square feet on the east end.

Figure 2. Results from chemical removal of rubber at Port au Prince (ARA)

The process is relatively slow and somewhat manually intensive, which may be an advantage in a labor-rich environment such as Haiti, but which makes the process very expensive in places such as Europe and the United States. And this provided an opportunity for a new business. As I wrote first in “Waterjetting Technology”:

One of the fascinating stories of the waterjet cleaning industry is that of Bob White, and his wife Donna. In 1972 Mr. White was a small painting contractor who unsuccessfully tried to clean the rubber deposits left from the wheels of landing aircraft from the runway at McClellan Air Force Base in California (now closed). Although able to remove material at only 60 sq ft/hr, he was convinced, particularly after seeing that the state of the art system was a chemical treatment, that waterjetting was the answer. Through a combination of loans from a variety of sources to the tune of $180,000 he built a four-pump, 24 nozzle spray bar system, initially operating at 10,000 psi and went into business. By driving himself through the night and thus being able to underbid the competition he took the first 25 of 28 jobs which were bid, and by the end of that year he had paid off his loans. By 1977 he had 5 rigs on the road around the country and was anticipating his first million dollar year.

Figure 3. Bob White (From the Duck Book).

After the first year on the road it was found, for most applications, that the jets removed the rubber better at 5,000 to 6,000 psi rather than at 10.000 psi and there was the added risk that at the higher pressure the water would either damage or polish the underlying concrete, depending on its quality and that of the aggregate contained. By supplying the flow from each pump to a six nozzle section of the spray bar it was possible to isolate a section should it have a problem, while still operating the rest of the units.

Figure 4. Bob's early rig (ibid)

The rig used spray bars fitted with 36 nozzles of hardened steel, 0.062 inch orifice diameters with a 30 degree spread, required to give 1 inch of coverage at a 0.75 inch standoff used. Other available equipment used 2,750 hp pump units to supply 0.078 inch diameter jets held one-inch apart, and with up to 96 nozzles on the spray bar. Such a unit could clean paint build up over 0.18 inch thick at a rate of 13,000 sq ft/hr, at a cost of $0.064/sq ft. Lowering the nozzle diameter to 0.04 inches resulted in a bar 94 inches long which when held an inch and a half above the surface, at 7,000 psi would allow cleaning at the rate of 60 ft/min, for a combined rate of 40,000 – 50,000 sq. ft./hr. The cost was estimated at $0.037 to $0.05 per sq ft.

In 1974 White was winning contracts at $0.045 per sq ft, and going below $0.032 per sq ft to get others. He had at that time 34 competitors, and yet grossed $280,000 that year. In 1975 he was bidding runway cleaning at less than $0.022 per sq ft for larger areas. Nozzle life was on the order of 50 hours for the stainless steel tips, and 250 hours for the steel holders. In January of 1978 Bob White discovered he had cancer and although successfully treated by 1980 he had sold off his rigs to highway painting contractors while he himself had turned to publishing.

He was sadly reported as being murdered in Belize in 1988. He was a true Pioneer of the industry.

Runway cleaning has progressed considerably since those early days and modern systems use higher pressures, in part to reduce the amount of contaminated water that is produced, since the cost of collection and disposal becomes significant. There is also a marriage of chemical pre-treatment and waterblasting which is shown in a video here.

But the ability of the waterjet system to discriminately remove the overlying coating (rubber) without damage to the underlying surface led on to other applications, which I will cover in the next few posts.